1. Field of the Invention
The present invention relates to a waveguide system for measuring the output characteristics of magnetrons which are microwave oscillators, and more particularly to a support for a waveguide system capable of measuring the output characteristics of a plurality of magnetrons having different dimensions.
2. Description of the Prior Art
Referring to FIGS. 1A and 1B, there is illustrated a waveguide system used as a conventional device for measuring output characteristics of magnetrons. As shown in FIGS. 1A and 1B, the waveguide system comprises a support 1, a taper type waveguide 2 hermetically coupled at one end thereof to one end of the support 1, a double slug tuner 3 hermetically coupled at one end thereof to the other end of the waveguide 2, a directional coupler 4 hermetically coupled at one end thereof to the other end of the double slug tuner 3, and a dummy load 5 hermetically coupled to the other end of the directional coupler 4. To the support 1 is coupled a magnetron 6. The waveguide 2 serves to eliminate a reflection coefficient based variations of the microwave. On the other hand, the double slug tuner 3 serves to optionally provide a reflection coefficient of the microwave. The directional coupler 4 senses the output characteristic of the microwave. The dummy load 5 is used as a reflectionless terminator for attenuating the microwave passing the directional coupler 4, to remove it.
When the characteristic of a magnetron is to be measured by using the waveguide system with the above-mentioned construction, an antenna 7 (see FIG. 1A) of the magnetron, which is denoted by the reference numeral 6, is coupled to the launcher 1. As electric power is applied to the waveguide system, an impedance between the support 1 and a load is determined depending on the vertical dimension of a back flange 8 (see FIG. 1A) of the support 1. Microwave energy generated in the interior of magnetron 6 is transferred to the waveguide system. At this time, in order to find the output characteristic of magnetron under the condition that no reflected wave is basically present, the coupling degree between the support 1 and the antenna 7, which is an output unit of the magnetron 6 should be properly determined for maintaining the matching condition of impedance.
FIG. 2A shows a condition where a standard support and a magnetron are coupled. Where the height of the antenna 7a of magnetron is about 29 mm to about 32 mm, it is possible to couple the magnetron 6a to the standard support 1a as shown in FIG. 2A and to measure the output characteristic of magnetron without any difficulty. A dimension of the support as shown in FIG. 2A is 54.6 mm. Where the height of antenna 7b is 20 mm, (See FIG. 2B where a dimension of the support is 25 mm) however, the above-mentioned coupling degree can not be accomplished. As a result, the matching condition of impedance can not be maintained, making it impossible to measure the characteristic of magnetron. Consequently, an exclusive waveguide system which is equipped with an exclusive support 1b for a magnetron 6b with an antenna of 20 mm, as shown in FIG. 2B must be used. Such an exclusive waveguide system can be effectively used in laboratory level measurement. Where mass measurement is carried out using the same exclusive waveguide system, however, the total cost for the measurement is very expensive, due to the extensive time required for replacing the supports and the taper type waveguides and the difficulty in installing an additional exclusive system.